a) Field of the Invention
The invention is directed to a testing arrangement for testing the dielectric strength of liquid insulating media which has a test cell comprising an interior space for receiving the insulating medium to be tested and a first test electrode and a second test electrode for generating an electric field in a test volume of the test cell.
b) Description of the Related Art
A testing arrangement for testing dielectric strength of liquid insulating media of the type mentioned above is known, for example, from DE 25 16 991 A1. Also, there are standards dealing with the testing of the dielectric strength of liquid insulating media by means of testing arrangements of the type mentioned above; IEC 60156 or ASTM D 1816 are cited as examples. The testing arrangement or testing arrangements known from DE 25 16991 A1 which correspond to the above-cited relevant standards require a large sample amount of insulating medium for testing. However, the costs for disposal of this insulating medium are high due to its toxicity. Also, a test can only be carried out when such a large sample amount is available at all. When this is not the case, for example, in high-voltage switches containing insulating oil, a measurement of the dielectric strength cannot be taken. Another disadvantage is that the actual test volume of known testing arrangements is small in proportion to the interiors of the test cells, which has a negative impact on the reproducibility of the measurements. As a result of the large interior spaces of the test cells which are filled with the insulating medium to be tested, solids from the insulating medium to be tested deposit in the test cell in spite of active homogenization, e.g., agitation, which leads to increased expenditure on cleaning and ultimately falsifies the measurement results. The breakdown voltages that are determined with the known testing arrangements exhibit stochastically distributed measurement errors with undesirably large scattering for a given insulating medium to be tested, even in the same testing arrangement.